1. Field of the Invention
This invention relates to a connector device for connecting the electric device on the interchangeable lens side and the electric device of a camera body.
2. Related Background Art
In interchangeable lens type cameras using a rotatively mountable-dismountable type bayonet mount for coupling or uncoupling an interchangeable lens with a camera body by clockwise or counter-clockwise rotation thereof, electric circuits have recently been provided on the interchangeable lens side and the camera body side, respectively, so that giving and receiving of various types of information such as information for automatic exposure control and information for automatic focus adjustment may be effected therebetween, and a camera provided with a number of connectors for giving and receiving of those signals near the mount has become known.
That is, as shown in FIGS. 1, 2, 6, 7 and 8 of the accompanying drawings, a camera side bayonet mount 1, a fixing lock pin 2 used during the mounting of the lens side mount and a contact seat (terminal bed) 3 forming the camera side connector are secured to the front face of the camera body 4 of a camera A, and on the contact seat 3, contact pins (terminals) 3.sub.a comprising a plurality of (in the illustrated example, seven) contact pins 3.sub.a1 -3.sub.a7 are biased so as to project flush with the front face of the contact seat 3 by contact springs 3.sub.b comprising contact springs 3.sub.b1 -3.sub.b7, and the contact pins 3.sub.a1 -3.sub.a7 are connected to a camera body side electric device 6 by a flexible printed plate 5. On the other hand, an interchangeable lens B holds a photo-taking lens unit 7, and a lens side bayonet mount 8, a plot-like lock groove 9 engageable by the camera side lock pin 2 and a contact seat (terminal bed) 10 constituting a lens side connector are secured to the rear end surface of the photo-taking lens unit, and contact pins (terminals) 10.sub.a comprising a plurality of (in the illustrated example, seven) contact pins 10.sub.a1 -10.sub.a7 are fixed to the contact seat 10 so that the rear end portions thereof are flush with one another, and the contact pins 10.sub.a1 -10.sub.a7 are connected to a lens side electric device 12 through a flexible printed plate 11. The camera side bayonet mount 1 is formed with three clicks 1.sub.a -1.sub.c, and the lens side bayonet mount 8 is formed with three clicks 8.sub.a -8.sub.c.
With the interchangeable lens B being mounted on the camera A by means of the respective bayonet mounts, the surfaces of the both mounts overlap each other (the clicks 1.sub.a -1.sub.c and 8.sub.a -8.sub.c of the both mounts 1 and 8 are rotated from their non-overlapping state into their overlapping state) as shown in FIG. 6, the camera body side contact pins 3.sub.a are brought into contact with the lens side contact pins 10.sub.a by the contact springs 3.sub.b, and the contact pins 3.sub.a1 -3.sub.a7 are connected to the contact pins 10.sub.a1 -10.sub.a7, respectively, so that the camera body side electric device 6 and the lens side electric device 12 effect giving and receiving of electrical signals therebetween.
As regards the connecting operation of the contact pins resulting from the mounting of the interchangeable lens B, when the lens side contact seat 10 is moved in the direction of arrow C in accordance with the rotative mounting of the interchangeable lens B as shown in FIG. 1, the contact pins 3.sub.a7 -3.sub.a1 of the camera body side contact seat 3 are successively pushed by the inclinded surface 10.sub.b at the end of the lens side contact seat 10 to compress the contact springs 3.sub.b7 -3.sub.b1. In this state, the contact pins 3.sub.a7 -3.sub.a1 are alternately pressed against and slid relative to the surface of the lens side contact seat 10 and the lens side contact pins 10.sub.a1 -10.sub.a7 so that at the point of time whereat the mounting is completed, the contact pins 3.sub.a1, 3.sub.a2, . . . , 3.sub.a7 and 10.sub.a1, 10.sub.a2, . . . , 10.sub.a7 contact each other on a common plane.
However, in the connector of the prior art as shown in FIGS. 1 and 2, each time the interchangeable lens B is mounted or dismounted with respect to the camera A, the lens side contact pin 10.sub.a1 slides on the camera body side contact pins 3.sub.a7 -3.sub.a1, the contact pin 10.sub.a2 slides on the contact pins 3.sub.a7 -3.sub.a2, and likewise the contact pin 10.sub.a7 slides on the contact pin 3.sub.a7. Accordingly, the camera body side contact pin 3.sub.a7 reciprocally slides on the lens side contact pins 10.sub.a1 -10.sub.a7, the contact pin 3.sub.a6 reciprocally slides on the contact pins 10.sub.a1 -10.sub.a6, and likewise the contact pin 3.sub.a1 reciprocally slides on the contact pin 10.sub.a1. Frequent repetition of mounting and dismounting has led to the occurrence of electrical problems such as decreased insulation resistance between the contacts and short-circuiting between the contacts caused by metal powder resulting from the abrasion of the contact pins, increased contact resistance caused by the oxidized films of the contact portions resulting from the peeling of the gold plating of the contact portions, and increased contact resistance caused by the adherence of the abrasion powder of the contact seats to the contact portions. These problems, in turn have led to poor durability and lack of reliability of prior art connectors shown in FIGS. 1 and 2.
Means for reducing the contact pressure between the contacts has been used to prevent such problems. However, it has been difficult to ensure contact resistance in devices which require low contact resistance, for example, terminals for power sources.